ancestorForWhichThisIsAPresentationalChild shouldn't create parent AXObject

Source/modules/accessibility/AXLayoutObject.cpp

 /*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 1226 matching lines @@
     // case SeparatorRole:
         return true;
     default:
         return false;
     }
 }
 
 AXObject* AXLayoutObject::ancestorForWhichThisIsAPresentationalChild() const
 {
     // Walk the parent chain looking for a parent that has presentational children
-    AXObject* parent = parentObject();
+    AXObject* parent = parentObjectIfExists();
     while (parent) {
         if (parent->ariaRoleHasPresentationalChildren())
             break;
 
         // The descendants of a AXMenuList that are AXLayoutObjects are all
         // presentational. (The real descendants are a AXMenuListPopup and
         // AXMenuListOptions, which are not AXLayoutObjects.)
         if (parent->isMenuList())
             break;
 
@@ skipping 1250 matching lines @@
         if (label && label->layoutObject()) {
             LayoutRect labelRect = axObjectCache().getOrCreate(label)->elementRect();
             result.unite(labelRect);
         }
     }
 
     return result;
 }
 
 } // namespace blink